A lot has changed since President Donald Trump picked Brett Kavanaugh in July as his nominee to the Supreme Court. At the time, Kavanaugh was well-known in conservative circles as a longtime judge on the D.C. Circuit Court of Appeals, often referred to as the second-highest court in the land.

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Now, he is facing a historic test of his credibility in the court of public opinion as he testifies before the Senate Judiciary Committee, facing off against Christine Blasey Ford, the woman who has accused him of sexually assaulting her while they both were in high school.

Kavanaugh has said it never happened, and he denies as well allegations of sexual misconduct by two other women. He survived tough questioning about his legal career in his initial confirmation hearings but how he comes across Thursday will likely determine his fate among the men and women who will judge -- and vote on -- whether he is fit for the court: the 100 members of the United States Senate.

Kavanaugh, 53, is sure to stress his record on the federal appeals court, beginning in 2006, as he defends his reputation. But he knows that Senate Democrats will cite the allegations from his high school and college days -- and perhaps after that -- and note that, if confirmed, he could reasonably expect to serve on the Supreme Court well into the middle of the century. President Trump has said that is a major reason he chose him.

A native of Washington, D.C., Kavanaugh attended Yale for both his undergraduate and law degrees, graduating law school cum laude in 1990. Kavanaugh then clerked for appellate judges Walter Stapleton and Alex Kozinski before clerking for Justice Kennedy – whose seat Kavanaugh would take if confirmed.

In the mid-1990s, Kavanaugh joined Kenneth Starr’s independent counsel team investigating President Bill Clinton and ultimately helped write the Starr Report to Congress. The report outlined in broad detail grounds on which to impeach President Clinton for his role in the Monica Lewinsky scandal. A decade later, Kavanaugh penned a law review article expressing second thoughts about whether presidents should be subjected to the burdens of prosecution and investigation. Kavanaugh’s evolved view on the subject could have implications for President Trump.

After a stint in private practice, Kavanaugh then joined the George W. Bush White House as an associate counsel and then as an assistant to the president.

In 2006 – after a grueling three-year confirmation process – Kavanaugh was confirmed to the D.C. Circuit Court of Appeals.

“From the notorious Starr report, to the Florida recount, to the president's secrecy and privilege claims to post-9/11 legislative battles including the Victims Compensation Fund, to ideological judicial nomination fights, if there has been a partisan political fight that needed a very bright legal foot soldier in the last decade, Brett Kavanaugh was probably there,” Sen. Chuck Schumer, D-N.Y., said during Kavanaugh’s 2006 confirmation hearing.

But conservatives perceive Kavanaugh’s time as a Republican operative favorably, and his connections from years in the executive branch could serve to soothe Republicans ahead of what could very well be a confirmation fight.

"I have had the privilege of working with many fine people in my two decades of White House service over three Administrations,” Anita McBride, former assistant to President George W. Bush, told ABC News in a statement. “Brett Kavanaugh is hands down among the finest.”